A hydrocarbon fire inflicts initial damage by directly heating metal beyond its limits and destroying the equipment or building. One way to mitigate this damage is to install fireproofing of structural steel. Conventional concrete, lightweight concrete and brick give a satisfactory degree of protection to metal assemblies for a period of time. The standard time-temperature curve is defined in ASTM E-119 and represents a wood fire that does not reach 3400°F (1870°C) for 4 hrs.
Explanation of the purpose and intent of the IRC, Table R402.1.1, footnote h. Explains how mis-interpretations have been used to bypass the intended code requirements for continuous insulation.